Optical and ophthalmic glass with refractive indices greater than or equal to 1.56, Abbe numbers greater than or equal to 40 and densities less than or equal to 2.70 g/cm3

Abstract

An optical and ophthalmic glass with high refractive index, high Abbe number and low density, which is distinguished by good chemical stability, good crystallization behavior and capability for chemical hardening, comprises (in % by weight): SiO2-47 to 75 B2O3-1 to 20 Al2O3-0 to 10 P2O5-0 to 5 Li2O-0 to 15 Na2O-0 to 10 K2O-0 to 10 CaO-0 to 20 MgO-0 to 15 SrO-0 to 4 BaO-0 to 4 ZnO-0 to 5 TiO2-1 to 15 ZrO2-0 to 8 Nb2O5-0 to 5 and F--0 to 5.

We claim: 
     
       1. An optical and ophthalmic glass with a refractive index greater than or equal to 1.56, an Abbe number greater than or equal to 40 and a density less than or equal to 2.70 g/cm 3 , consisting essentially of (in % by weight): SiO 2  --49-68   B 2  O 3  --3-8   Al 2  O 3  --0.5-3   P 2  O 5  --0-1.5   sum of SiO 2 , B 2  O 3 , Al 2  O 3  and P 2  O 5  --60-78   Li 2  O--3-8   Na 2  O--4-10   K 2  O--0-10   sum of M 2  O (M=Li, Na, K)--9-17   CaO--2-6   MgO--0-3   SrO--0-4   BaO--0-4   ZnO--0-2.97   TiO 2  --5-12.8   ZrO 2  --0-6   Nb 2  O 5  --0.15-5   F---0-5   sum of CaO, MgO, SrO, BaO, ZnO--1.5-6   Y 2  O 3  --0-3.   
     
     
       2. An optical and ophthalmic glass with a refractive index greater than or equal to 1.56, an Abbe number greater than or equal to 40 and a density less than or equal to 2.70 g/cm 3 , consisting essentially of (in % by weight): SiO 2  --49-68   B 2  O 3  --3-8   Al 2  O 3  --0.5-3   P 2  O 5  --0-1.5   sum of SiO 2 , B 2  O 3 , Al 2  O 3  and P 2  O 5  --60-78   Li 2  O--3-8   Na 2  O--5-7   K 2  O--0-6   sum of M 2  O (M=Li, Na, K)--15-17   CaO--0-5   MgO--0-3   SrO--0-4   BaO--0-4   ZnO--0-2.97   TiO 2  --5-12   ZrO 2  --0-6   Nb 2  O 5  --0.15-5   F---0-1   sum of CaO, MgO, SrO, BaO, ZnO--1.5-6   Y 2  O 3  --0-3.   
     
     
       3. An optical and ophthalmic glass with a refractive index greater than or equal to 1.56, an Abbe number greater than or equal to 40 and a density less than or equal to 2.70 g/cm 3 , consisting essentially of (in % by weight): SiO 2  --49 to 68   B 2  O 3  --8 to 14   Al 2  O 3  --0.5 to 3   GeO 2  --0 to 3   P 2  O 5  --0 to 1.5   sum of SiO 2 , B 2  O 3 , Al 2  O 3  and P 2  O 5  --60 to 75   Li 2  O--6 to 12   Na 2  O--0.5 to 4.5   K 2  O--0 to 2   sum of Li 2  O, K 2  O and Na 2  O--8 to 15   MgO--1 to 6   CaO--2 to 8   ZnO--0 to 5   sum of MgO, CaO, ZnO--3 to 18   TiO 2  --4 to 9.5   ZrO 2  --0 to 3   Nb 2  O 5  --0.3 to 5   NaF--1 to 3.5   Y 2  O 3  --0 to 4.   
     
     
       4. An optical and ophthalmic glass with a refractive index greater than or equal to 1.56, an Abbe number greater than or equal to 40 and a density less than or equal to 2.70 g/cm 3 , consisting essentially of (in % by weight): SiO 2  --47 to 58   B 2  O 3  --12 to 16   Al 2  O 3  --0.5 to 2   Sum of SiO 2 , B 2  O 3  and Al 2  O 3  --68 to 78   Li 2  O--10 to 15   Na 2  O--4 to 6   K 2  O--0 to 1   Sum of Li 2  O, K 2  O and Na 2  O--15 to 17   CaO--4 to 8   MgO--4 to 7   ZnO--0 to 1   sum of CaO, MgO and ZnO--8 to 14   TiO 2  --7 to 10   ZrO 2  --0 to 2   Nb 2  O 5  --0 to 2   F---0.4 to 1.   
     
     
       5. An optical and ophthalmic glass with a refractive index greater than or equal to 1.56, an Abbe number greater than or equal to 40 and a density less than or equal to 2.70 g/cm 3 , consisting essentially of (in % by weight): SiO 2  --47 to 51   B 2  O 3  --10 to 18   Al 2  O 3  --0 to 4   Sum of SiO 2 , B 2  O 3  and Al 2  O 3  --58 to 62   Li 2  O--4 to 12   Na 2  O--2 to 6   K 2  O--0 to 4   Sum of Li 2  O, K 2  O and Na 2  O--8 to 16   CaO--1 to 7   MgO--0 to 5   ZnO--0 to 4   sum of CaO, MgO and ZnO--5 to 12   TiO 2  --5 to 8   ZrO 2  --0 to 2   Nb 2  O 5  --0 to 3   F---0.4 to 1.   
     
     
       6. A glass of claim 1, further consisting essentially of (in % by weight): SrO--0 to 4   BaO--0 to 4   PbO--0 to 5.   
     
     
       7. A glass of claim 2 further consisting essentially of (in % by weight): SrO--0 to 4   BaO--0 to 4   PbO--0 to 5.   
     
     
       8. A glass of claim 6, wherein the sum of SrO, BaO, ZnO and PbO (in % by weight), is less than or equal to 10. 
     
     
       9. A glass of claim 1, further consisting essentially of Nb 2  O 5  --0 to 5   Y 2  O 3  --0 to 4   La 2  O 3  --0 to 8   Ta 2  O 5  --0 to 3   SnO 2  --0 to 3.0 in addition to or instead of NaF   Bi 2  O 3  --0 to 2.0   Yb 2  O 3  --0 to 3.5   Ce 2  O 3  --0 to 3   Sb 2  O 3  --0 to 2.5   TeO 2  --0 to 2   SeO 2  --0 to 2   WO 3  --0 to 5.   
     
     
       10. A glass of claim 1, further consisting essentially of (in % by weight): La 2  O 3  --0 to 8   WO 3  --0 to 5   Ta 2  O 5  --0 to 3.   
     
     
       11. An optical and ophthalmic glass with a refractive index greater than or equal to 1.56, an Abbe number greater than or equal to 40 and a density less than or equal to 2.70 g/cm 3 , consisting essentially of (in % by weight): SiO 2  --49-68   B 2  O 3  --3-8   Al 2  O 3  --0.5-3   P 2  O 5  --0-1.5   sum of SiO 2 , B 2  O 3 , Al 2  O 3  and P 2  O 5  --60-78   Li 2  O--3-8   Na 2  O--4-10   K 2  O--0-10   sum of M 2  O (M=Li, Na, K)--9-17   CaO--2-6   MgO--0-3   SrO--0-4   BaO--0-4   ZnO--0-2.97   TiO 2  --5-12.8   ZrO 2  --0-6   Nb 2  O 5  --0-3   F---0.5-5   sum of CaO, MgO, SrO, BaO, ZnO--1.5-6   Y 2  O 3  --0-3.   
     
     
       12. An optical and ophthalmic glass with a refractive index greater than or equal to 1.56, an Abbe number greater than or equal to 40 and a density less than or equal to 2.70 g/cm 3 , consisting essentially of (in % by weight): SiO 2  --49-68   B 2  O 3  --3-8   Al 2  O 3  --0.5-3   P 2  O 5  --0-1.5   sum of SiO 2 , B 2  O 3 , Al 2  O 3  and P 2  O 5  --60-78   Li 2  O--3-8   Na 2  O--5-7   K 2  O--0-6   sum of M 2  O (M=Li, Na, K)--15-17   CaO--0-5   MgO--0-3   SrO--0-4   BaO--0-4   ZnO--0-2.97   TiO 2  --5-12   ZrO 2  --0-6   Nb 2  O 5  --0-3   F---0.5-1   sum of CaO, MgO, SrO, BaO, ZnO--1.5-6   Y 2  O 3  --0-3.